Prevention strategies will be developed to take advantage of the metabolic and behavioral risk factors for NIDDM which have been identified in research with the Pima Indians and elsewhere. Obesity, impaired glucose tolerance, hyperinsulinemia, physical inactivity, and high fat diet have been implicated as risk factors for NIDDM. Since these factors are potentially reversible with behavioral and pharmacologic therapy, strategies for prevention will be developed and tested. A feasibility study of diet and exercise treatment has been conducted among overweight Pima Indians with normal glucose tolerance. Knowledge and experience gained from this pilot study will be used in planning and implementing the national, multicenter clinical trial in prevention of NIDDM, in which the investigators will participate.